Hair dryers are well known and broadly used by barbers, beauticians, hair stylist and by individuals in their own homes and hotel rooms. These Hair dryers are use to apply warm or more commonly hot air to dry an individual's hair. Such dryers have also been combined with a brush or comb for grooming the hair as it is being dried. The problem is that in drying the hair, there is a risk that the hair is made too dry by the hot air and may be damaged. Further, as the hair becomes dry, the roots of the hair and scalp are subjected to the hot air which may be painful and may cause minor bums and flaking of the scalp.
Therefore, it is desirable to know the moisture content of the hair and to takes steps to limit the drying effect of a dryer. For example, it is known to dispose a moisture sensor in the circulating air in a hair drying hood. However, this known method of moisture measurement is not applicable to hand held dryers.
Furthermore, Hair dryers which have electrodes arranged on an accessory which comes into contact with the hair during drying are known. In such dryers, the moisture is measured on the basis of the resistance or capacitance of the hair between the electrodes. To be more specific, a U.S. Pat. No. 4,877,042 of Downey discloses a dynamic hair grooming appliance such as a comb, a heated hair styler or a curler including a moisture sensing device and an indicator that allows the user to control the dryness of the hair during styling.
A more recent approach to controlling the moisture content of hair during styling is disclosed in a U.S. Pat. No. 6,026,821 of Last. As disclosed therein, the moistness of the hair is controlled by means of a detector which compares the amount of radiant energy in two absorption bands in the spectrum of light emitted by an infra red source and reflected by the hair. One of the absorption bands is caused by water in the hair. The amount of radiant energy in this absorption band changes significantly during the drying of the hair. The other absorption band is caused by keratin in the hair. The energy in this band changes to a much smaller extent during the drying of the hair. The intensity ratio of the two bands is an indicator for the moistness of the hair and can be employed to control the temperature and/or the air flow of the hair dryer.
Notwithstanding the above, it is presently believed that there may be a commercial market for an improved automatic Hair dryer in accordance with the present invention. There should be a market demand because such dryers reduce the likelihood of damaging a person's hair, are relatively easy to use for a professional or amateur, durable and can be sold at a reasonable price.